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Multifunkční objekt v Českých Budějovicích / The Multipurpose House in České BudějoviceŠpačková, Eva January 2016 (has links)
The subject of this thesis is the design and assessment of the supporting structure multifunctional building in the Czech Budejovice . The construction of a sphere with a maximum diameter of 30 m and a height of 19.5 meters the highest point . The supporting structure consists of curved ribs , elevator shaft and ceiling beams . The structure is designed in 4 versions . Two variants are made of steel, the third option is wooden and the latest version solves a combination of wood and steel. In the variant selected is done loading , ultimate limit state, serviceability limit state , fire resistance and compounds selected details.
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Contribution to digital microrobotics : modeling, design and fabrication of curved beams, U-shaped actuators and multistable microrobots / Contribution à la microrobotique numérique : modélisation, conception et fabrication de poutres bistables, d'actionneurs en U et de microrobots multistablesHussein, Hussein 11 December 2015 (has links)
Un nombre de sujets concernant la microrobotique numérique ont été abordés dans le cadre de cette the` se. Une nouvelle génération du microrobot numérique ”DiMiBot” a e´ te´ proposé ce qui rend le DiMiBot plus précis, plus contrôlable et plus petit. La nouvelle structure est formée de deux modules multistables seulement, ce qui ajoute des fonctionnalités´ s importantes comme l’augmentation du nombre de positions avec une taille plus réduite et la capacité´ de réaliser des trajectoires complexes dans l’espace de travail. Le principe du nouveau module multistable combine les avantages des microactionneurs pas à pas en termes du principe et du concept numérique en termes de la répétabilité et la robustesse en boucle ouverte. Un mécanisme de positionnement précis, capable de compenser les incertitudes de fabrication a e´ te´ développé et utilise´ pour assurer un positionnement précis. En parallèle, des modèles analytiques ont e´ te´ développés pour les principaux composants dans le DiMiBot: poutres flambées préformées et actionneurs e´ électrothermiques en U. Des méthodes de conception ont été développées par la suite qui permettent de choisir les dimensions optimales garantissant les performances requises en respectant les spécifications et limites de design. Des prototypes de modules multistables, fabrique´ s dans la salle Blanche MIMENTO, ont montré´ un bon Fonctionnement dans les expériences. / A number of topics concerning digital microrobotics were addressed in this thesis. A new generation of the digital microrobot ”DiMiBot” was proposed with several advantages making the DiMiBot more accurate, more controllable and smaller. The new structure consists of only two multistable modules which adds some important features such as increasing the number of positions with smaller size and the ability to realize complex trajectories in the workspace. The principle of the new multistable module combines the advantages of the stepping microactuators in terms of the principle and of the digital concept in terms of the repeatability and robustness without feedback. The accuracy is ensured with an accurate positioning mechanism that compensate the fabrication tolerances. In parallel, analytical models was developed for the main components in the DiMiBot: preshaped curved beams and U-shaped electrothermal actuators. Subsequently, design methods were developed that allow choosing the optimal dimensions that ensure the desired outputs and respecting the design specifications and limitations. Multistable module prototypes, fabricated in the clean room MIMENTO, showed a proper functioning in the experiments.
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Responsive Textile Geometries : Vanadisbadet RevisedAidas, Nina January 2011 (has links)
How can principles found in textile behaviour be translated into architectural expression? With water as a program in context of a new bath in Vanadislunden, Stockholm, this project studies how a rigid material can be percieved as soft and flexible.
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Local Thermal Equilibrium on Curved Spacetimes and Linear Cosmological Perturbation TheoryEltzner, Benjamin 29 May 2013 (has links)
In this work the extension of the criterion for local thermal equilibrium by Buchholz, Ojima and Roos to curved spacetime as introduced by Schlemmer is investigated. Several problems are identified and especially the instability under time evolution which was already observed by Schlemmer is inspected. An alternative approach to local thermal equilibrium in quantum field theories on curved spacetimes is presented and discussed. In the following the dynamic system of the linear field and matter perturbations in the generic model of inflation is studied in the view of ambiguity of quantisation. In the last part the compatibility of the temperature fluctuations of the cosmic microwave background radiation with local thermal equilibrium is investigated.:1. Introduction 5
2. Technical Background 10
2.1. The Free Scalar Field on a Globally Hyperbolic Spacetime . . . . . . 10
2.1.1. Construction of the Scalar Field . . . . . . . . . . . . . . . . . 10
2.1.2. Algebra of Wick Products . . . . . . . . . . . . . . . . . . . . 13
2.1.3. Local Covariance Principle . . . . . . . . . . . . . . . . . . . . 17
2.2. Local Thermal Equilibirum . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.1. Global Thermodynamic Equilibrium - KMS States . . . . . . 21
2.2.2. Local Thermal Observables . . . . . . . . . . . . . . . . . . . 24
2.2.3. LTE on Flat Spacetime . . . . . . . . . . . . . . . . . . . . . . 29
2.2.4. LTE in Cosmological Spacetimes . . . . . . . . . . . . . . . . 32
2.3. Linear Scalar Cosmological Perturbations . . . . . . . . . . . . . . . . 34
2.3.1. Robertson-Walker Cosmology . . . . . . . . . . . . . . . . . . 35
2.3.2. Mathematical Background . . . . . . . . . . . . . . . . . . . . 38
2.3.3. Technical Framework and Formulae . . . . . . . . . . . . . . . 40
2.3.4. The Boltzmann Equation . . . . . . . . . . . . . . . . . . . . 46
2.3.5. The Sachs-Wolfe Effect for Adiabatic Perturbations . . . . . . 49
3. Towards a Refinement of the LTE Condition on Curved Spacetimes 54
3.1. Non-Minimal Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.1.1. Commutator Distribution . . . . . . . . . . . . . . . . . . . . 55
3.1.2. KMS Two-Point Function . . . . . . . . . . . . . . . . . . . . 57
3.1.3. Balanced Derivatives . . . . . . . . . . . . . . . . . . . . . . . 61
3.2. Conformally Static Spacetimes . . . . . . . . . . . . . . . . . . . . . . 65
3.2.1. Conformal KMS States . . . . . . . . . . . . . . . . . . . . . . 66
3.2.2. Extrinsic LTE in de Sitter Spacetime . . . . . . . . . . . . . . 71
3.3. Massive Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.3.1. Properties of the Model . . . . . . . . . . . . . . . . . . . . . 78
3.3.2. Bogoliubov Transformation . . . . . . . . . . . . . . . . . . . 80
3.3.3. Thermal Observables . . . . . . . . . . . . . . . . . . . . . . . 82
3.4. Towards an Alternative Concept . . . . . . . . . . . . . . . . . . . . . 91
3.4.1. Problems and Open Questions Concerning LTE . . . . . . . . 92
3.4.2. Dynamic Equations . . . . . . . . . . . . . . . . . . . . . . . . 94
3.4.3. Positivity Inequalities . . . . . . . . . . . . . . . . . . . . . . . 96
3.4.4. Macroobservable Interpretation . . . . . . . . . . . . . . . . . 100
3.5. An Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4. Cosmological Perturbation Theory 105
4.1. Dynamics of Perturbations in Inflation . . . . . . . . . . . . . . . . . 106
4.1.1. CCR Quantisation is Ambiguous . . . . . . . . . . . . . . . . 106
4.1.2. Canonical Symplectic Form . . . . . . . . . . . . . . . . . . . 111
4.1.3. The Algebraic Point of View . . . . . . . . . . . . . . . . . . . 117
4.2. LTE States in Cosmology . . . . . . . . . . . . . . . . . . . . . . . . 120
4.2.1. The Link to Fluid Dynamics . . . . . . . . . . . . . . . . . . . 120
4.2.2. Incompatibility of LTE with Sachs-Wolfe Effect . . . . . . . . 125
5. Conclusion and Outlook 131
A. Technical proofs 136
A.1. Proof of Lemma 3.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
A.2. Proof of Lemma 3.2.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
A.3. Proof of Lemma 3.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
A.4. Idea of Proof for Conjecture 3.4.3 . . . . . . . . . . . . . . . . . . . . 144
B. Introduction to Probability Theory 146
Bibliography 150
Correction of Lemma 3.1.2 155 / In dieser Arbeit wird die von Schlemmer eingeführte Erweiterung des Kriteriums für lokales thermisches Gleichgewicht in Quantenfeldtheorien von Buchholz, Ojima und Roos auf gekrümmte Raumzeiten untersucht. Dabei werden verschiedene Probleme identifiziert und insbesondere die bereits von Schlemmer gezeigte Instabilität unter Zeitentwicklung untersucht. Es wird eine alternative Herangehensweise an lokales thermisches Gleichgewicht in Quantenfeldtheorien auf gekrümmten Raumzeiten vorgestellt und deren Probleme diskutiert. Es wird dann eine Untersuchung des dynamischen Systems der linearen Feld- und Metrikstörungen im üblichen Inflationsmodell mit Blick auf Uneindeutigkeit der Quantisierung durchgeführt. Zuletzt werden die Temperaturfluktuationen der kosmischen Hintergrundstrahlung auf Kompatibilität mit lokalem thermalem Gleichgewicht überprüft.:1. Introduction 5
2. Technical Background 10
2.1. The Free Scalar Field on a Globally Hyperbolic Spacetime . . . . . . 10
2.1.1. Construction of the Scalar Field . . . . . . . . . . . . . . . . . 10
2.1.2. Algebra of Wick Products . . . . . . . . . . . . . . . . . . . . 13
2.1.3. Local Covariance Principle . . . . . . . . . . . . . . . . . . . . 17
2.2. Local Thermal Equilibirum . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.1. Global Thermodynamic Equilibrium - KMS States . . . . . . 21
2.2.2. Local Thermal Observables . . . . . . . . . . . . . . . . . . . 24
2.2.3. LTE on Flat Spacetime . . . . . . . . . . . . . . . . . . . . . . 29
2.2.4. LTE in Cosmological Spacetimes . . . . . . . . . . . . . . . . 32
2.3. Linear Scalar Cosmological Perturbations . . . . . . . . . . . . . . . . 34
2.3.1. Robertson-Walker Cosmology . . . . . . . . . . . . . . . . . . 35
2.3.2. Mathematical Background . . . . . . . . . . . . . . . . . . . . 38
2.3.3. Technical Framework and Formulae . . . . . . . . . . . . . . . 40
2.3.4. The Boltzmann Equation . . . . . . . . . . . . . . . . . . . . 46
2.3.5. The Sachs-Wolfe Effect for Adiabatic Perturbations . . . . . . 49
3. Towards a Refinement of the LTE Condition on Curved Spacetimes 54
3.1. Non-Minimal Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.1.1. Commutator Distribution . . . . . . . . . . . . . . . . . . . . 55
3.1.2. KMS Two-Point Function . . . . . . . . . . . . . . . . . . . . 57
3.1.3. Balanced Derivatives . . . . . . . . . . . . . . . . . . . . . . . 61
3.2. Conformally Static Spacetimes . . . . . . . . . . . . . . . . . . . . . . 65
3.2.1. Conformal KMS States . . . . . . . . . . . . . . . . . . . . . . 66
3.2.2. Extrinsic LTE in de Sitter Spacetime . . . . . . . . . . . . . . 71
3.3. Massive Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.3.1. Properties of the Model . . . . . . . . . . . . . . . . . . . . . 78
3.3.2. Bogoliubov Transformation . . . . . . . . . . . . . . . . . . . 80
3.3.3. Thermal Observables . . . . . . . . . . . . . . . . . . . . . . . 82
3.4. Towards an Alternative Concept . . . . . . . . . . . . . . . . . . . . . 91
3.4.1. Problems and Open Questions Concerning LTE . . . . . . . . 92
3.4.2. Dynamic Equations . . . . . . . . . . . . . . . . . . . . . . . . 94
3.4.3. Positivity Inequalities . . . . . . . . . . . . . . . . . . . . . . . 96
3.4.4. Macroobservable Interpretation . . . . . . . . . . . . . . . . . 100
3.5. An Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4. Cosmological Perturbation Theory 105
4.1. Dynamics of Perturbations in Inflation . . . . . . . . . . . . . . . . . 106
4.1.1. CCR Quantisation is Ambiguous . . . . . . . . . . . . . . . . 106
4.1.2. Canonical Symplectic Form . . . . . . . . . . . . . . . . . . . 111
4.1.3. The Algebraic Point of View . . . . . . . . . . . . . . . . . . . 117
4.2. LTE States in Cosmology . . . . . . . . . . . . . . . . . . . . . . . . 120
4.2.1. The Link to Fluid Dynamics . . . . . . . . . . . . . . . . . . . 120
4.2.2. Incompatibility of LTE with Sachs-Wolfe Effect . . . . . . . . 125
5. Conclusion and Outlook 131
A. Technical proofs 136
A.1. Proof of Lemma 3.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
A.2. Proof of Lemma 3.2.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
A.3. Proof of Lemma 3.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
A.4. Idea of Proof for Conjecture 3.4.3 . . . . . . . . . . . . . . . . . . . . 144
B. Introduction to Probability Theory 146
Bibliography 150
Correction of Lemma 3.1.2 155
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Lávka přes dálnici D1 v Bohumíně / Pedestrian bridge across the highway D1 in BohumínMuroň, Vlastimil January 2022 (has links)
The aim of final thesis is design and assessment of footbridge over highway D1 in Bohumín. The design is processed in two options. From these two options there is cable-stayed construction solved in greater detail. Because counstruction is in circular arch with small radius, it is necessary to contain real geometry to computational model. Model is created by beams and construction stages are included too. The construction is assessed for the ultimate and serviceability limit state according to valid standards. In the thesis is performed eigenvalue analysis and harmonic response of the construction. Detailed drawings are included too.
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Nelineární analýza bezstykové koleje v obloucích malého poloměru / Nonlinear analysis of continuous welded rail in curves of small radiusMurínová, Klára Unknown Date (has links)
The diploma thesis examines the influence of curve radius on continuous welded rail stability in a small radius curve. Attention is paid to curves with a radius less than 300 m. The first part of the thesis summarises the theory of continuous welded track and influence of track parameters on track stability. The second part of the thesis deals with constructing of the numerical model of a curved track with the observed behaviour of track under thermal loading with positive and negative temperature values. The variable values in the model are rail shapes and different radius. In the end, the shape of the track lateral deflection as a function of temperature are evaluated.
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Imaging Spin Textures on Curved Magnetic SurfacesStreubel, Robert 27 August 2015 (has links)
Gegenwärtige Bestrebungen materialwissenschaftlicher Forschung beschäftigen sich unter anderem mit der Überführung zweidimensionaler Elemente elektronischer, optischer, plasmonischer oder magnetischer Funktionalität in den dreidimensionalen (3D) Raum. Dieser Ansatz vermag mittels Krümmung und struktureller Topologie bereits vorhandene Eigenschaften abzuändern beziehungsweise neue Funktionalitäten bereitzustellen. Vor allem Vektoreigenschaften wie die Magnetisierung kondensierter Materie lassen sich aufgrund der Brechung der Inversionssymmetrie in gekrümmten Flächen stark beeinflussen. Neben der Entwicklung diverser Vorgänge zur Herstellung 3D magnetischer Gegenstände sind geeignete Untersuchungsmethoden wie beispielsweise tomografische Abbildungen der Magnetisierung von Nöten, die maßgeblich die physikalischen Eigenschaften bestimmen.
Die vorliegende Dissertationsschrift befasst sich mit der Abbildung von magnetischen Domänen in 3D gekrümmten Dünnschichten beruhend auf dem Effekt des zirkularen magnetischen Röntgendichroismus (XMCD). Die in diesem Zusammenhang entwickelte magnetische Röntgentomografie (MXT) basierend auf weicher Röntgenmikroskopie stellt eine zu Elektronenholografie und Neutronentomografie komplementäre Methodik dar, welche großes Anwendungspotential in der elementspezifischen Untersuchung magnetischer gekrümmter Flächen mit örtlicher Auflösung im Nanometerbereich aufweist. Die Schwierigkeit der Interpretation von Abbildungen magnetischer Strukturen in gekrümmten Flächen rührt von der Dreidimensionalität und der Vektoreigenschaft der Magnetisierung her. Die hierzu notwendigen Kenntnisse sind anhand von zwei topologisch verschiedenen Flächen in Form hemisphärischer Kappen und hohler Zylinder erschlossen worden. Die praktische Anwendung von MXT ist abschließend anhand der Rekonstruktion magnetischer Domänen in aufgerollten Dünnschichten mit zylindrischer Form verdeutlicht. / One of the foci of modern materials sciences is set on expanding conventional two-dimensional electronic, photonic, plasmonic and magnetic devices into the third dimension. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and three-dimensional (3D) shape. The degree of effect is particularly high for vector properties like the magnetization due to an emergent inversion symmetry breaking. Aside from capabilities to design and synthesize 3D magnetic architectures, proper characterization methods, such as magnetic tomographic imaging techniques, need to be developed to obtain a thorough understanding of the system’s response under external stimuli.
The main objective of this thesis is to develop a visualization technique that provides nanometer spatial resolution to image the peculiarities of the magnetic domain patterns on extended 3D curved surfaces. The proposed and realized concept of magnetic soft X-ray tomography (MXT), based on the X-ray magnetic circular dichroism (XMCD) effect with soft X-ray microscopies, has the potential to become a powerful tool to investigate element specifically an entirely new class of 3D magnetic objects with virtually any shape and magnetization. Imaging curved surfaces meets the challenge of three-dimensionality and requires a profound understanding of the recorded XMCD contrast. These experiences are gained by visualizing magnetic domain patterns on two distinct 3D curved surfaces, namely magnetic cap structures and rolled-up magnetic nanomembranes with cylindrical shape. The capability of MXT is demonstrated by reconstructing the magnetic domain patterns on 3D curved surfaces resembling hollow cylindrical objects.
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Solution Synthesis and Characterization of a Long and Curved Graphene Nanoribbon with Hybrid Cove–Armchair–Gulf Edge StructuresYang, Lin, Zheng, Wenhao, Osella, Silvio, Droste, Jörn, Komber, Hartmut, Liu, Kun, Böckmann, Steffen, Beljonne, David, Hansen, Michael Ryan, Bonn, Mischa, Wang, Hai I., Liu, Junzhi, Feng, Xinliang, Ma, Ji 22 April 2024 (has links)
Curved graphene nanoribbons (GNRs) with hybrid edge structures have recently attracted increasing attention due to their unique band structures and electronic properties as a result of their nonplanar conformation. This work reports the solution synthesis of a long and curved multi-edged GNR (cMGNR) with unprecedented cove–armchair–gulf edge structures. The synthesis involves an efficient A2B2-type Diels–Alder polymerization between a diethynyl-substituted prefused bichrysene monomer (3b) and a dicyclopenta[e,l]pyrene-5,11-dione derivative (6) followed by FeCl3-mediated Scholl oxidative cyclodehydrogenation of the obtained polyarylenes (P1). Model compounds 1a and 1b are first synthesized to examine the suitability and efficiency of the corresponding polymers for the Scholl reaction. The successful formation of cMGNR from polymer P1 bearing prefused bichrysene units is confirmed by FTIR, Raman, and solid-state NMR analyses. The cove-edge structure of the cMGNR imparts the ribbon with a unique nonplanar conformation as revealed by density functional theory (DFT) simulation, which effectively enhances its dispersibility in solution. The cMGNR has a narrow optical bandgap of 1.61 eV, as estimated from the UV–vis absorption spectrum, which is among the family of low-bandgap solution-synthesized GNRs. Moreover, the cMGNR exhibits a carrier mobility of ≈2 cm2 V−1 s−1 inferred from contact-free terahertz spectroscopy.
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Fases geométricas, quantização de Landau e computação quâantica holonômica para partículas neutras na presença de defeitos topológicosBakke Filho, Knut 06 August 2009 (has links)
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Previous issue date: 2009-08-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We start this work studying the appearance of geometric quantum phases as in the relativistic
as in the non-relativistic quantum dynamics of a neutral particle with permanent
magnetic and electric dipole moment which interacts with external electric and magnetic
fields in the presence of linear topological defects. We describe the linear topological
defects using the approach proposed by Katanaev and Volovich, where the topological
defects in solids are described by line elements which are solutions of the Einstein's equations
in the context of general relativity. We also analyze the in
uence of non-inertial
effects in the quantum dynamics of a neutral particle using two distinct reference frames
for the observers: one is the Fermi-Walker reference frame and another is a rotating frame.
As a result, we shall see that the difference between these two reference frames is in the
presence/absence of dragging effects of the spacetime which makes its in
uence on the
phase shift of the wave function of the neutral particle. In the following, we shall use our
study of geometric quantum phases to make an application on the Holonomic Quantum
Computation, where we shall show a new approach to implement the Holonomic Quantum
Computation via the interaction between the dipole moments of the neutral particle
and external fields and the presence of linear topological defects. Another applications for
the Holonomic Quantum Computation is based in the structure of the topological defects
in graphene layers. In the presence of topological defects, a graphene layer shows two
distinct phase shifts: one comes from the mix of Fermi points while the other phase shift
comes from the topology of the defect. To provide a geometric description for each phase
shift in the graphene layer, we use the Kaluza-Klein theory where we establish that the
extra dimension describes the Fermi points in the graphene layer. Hence, we can implement
the Holonomic Quantum Computation through the possibility to build cones and
anticones of graphite in such way we can control the quantum
uxes in graphene layers.
In the last part of this work, we study the Landau quantization for neutral particles as in
the relativistic dynamics and non-relativistic dynamics. In the non-relativistic dynamics,
we study the Landau quantization in the presence of topological defects as in an inertial
as in a non-inertial reference frame. In the relativistic quantum dynamics, we start our
study with the Landau quantization in the Minkowisky considering two different gauge
fields. At the end, we study the relativistic Landau quantization for neutral particles in
the Cosmic Dislocation spacetime. / Neste trabalho estudamos inicialmente o surgimento de fases geometricas nas dinâmicas quânticas relativística e não-relativística de uma partícula neutra que possui momento de
dipolo magnético e elétrico permanente interagindo com campos elétricos e magnéticos externos
na presença de defeitos topológicos lineares. Para descrevermos defeitos topológicos
lineares usamos a aproximação proposta por Katanaev e Volovich, onde defeitos lineares em sólidos são descritos por elementos de linha que são soluções das equações de Einstein
no contexto da relatividade geral. Analisamos também a
inuência de efeitos não-inerciais na dinâmica quântica de uma partícula neutra em dois tipos distintos de referenciais para
os observadores: um é o referencial de Fermi-Walker e outro é um referencial girante.
Vemos que a diferença entre dois referenciais está na presença/ausência de efeitos de arrasto
do espaço-tempo que irá influenciar diretamente na mudança de fase na funçãao de
onda da partícula neutra. Em seguida, usamos nosso estudo de fases geométricas para
fazer aplicações na Computação Quântica Holonômica onde mostramos uma nova maneira de implementar a Computação Quântica Holonômica através da interação entre momentos
de dipolo e campos externos e pela presença de defeitos topológicos lineares. Outra
aplicação para a Computação Quântica Holonômica está baseada na estrutura de defeitos
topológicos em um material chamado grafeno. Na presença de defeitos topológicos lineares,
esse material apresenta duas fases quânticas de origens distintas: uma da mistura
dos pontos de Fermi e outra da topologia do defeito. Para dar uma descrição geométrica para a origem de cada fase no grafeno usamos a Teoria de Kaluza-Klein, onde a dimensão extra sugerida por esta teoria descreve os pontos de Fermi no grafeno. Portanto, a implementação da Computação Quântica Holonômica no grafeno está baseada na possibilidade
de construir cones e anticones de grafite de tal maneira que se possa controlar os fluxos
quânticos no grafeno. Na última parte deste trabalho estudamos a quantização de Landau
para partículas neutras tanto na dinâmica não-relativística quanto na dinâmica relativística. Na dinâmica não-relativítica, estudamos a quantização de Landau na presença
de defeitos em um referecial inercial e, em seguida, em um referencial nãoo-inercial. Na
dinâmica relativística, estudamos inicialmente a quantização de Landau no espaço-tempo
plano em duas configurações de campos diferentes. Por fim, estudamos a quantização de
Landau relativística para partículas neutras no espaço-tempo da deslocação cósmica.
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[en] COSSERAT RODS AND THEIR APPLICATION TO DRILL-STRING DYNAMICS / [es] ESTRUCTURAS UNIDIMENSIONALES DE COSSERAT APLICADAS A LA DINÁMICA DE COLUMNAS DE PERFORACIÓN / [pt] ESTRUTURAS UNIDIMENSIONAIS DE COSSERAT APLICADAS À DINÂMICA DE COLUNAS DE PERFURAÇÃOHECTOR EDUARDO GOICOECHEA MANUEL 13 June 2023 (has links)
[pt] Nesta tese, a teoria das hastes de Cosserat é revisitada e aplicada à
dinâmica de coluna de perfuração. O objetivo é estudar o comportamento
dessas estruturas dentro de poços de petróleo curvos. Para atingir este objetivo,
um modelo estrutural determinístico é construído onde as tubos de perfuração
(drill-pipes) e o conjunto de fundo (bottom hole assembly) são considerados
como uma estrutura unidimensional de Cosserat. Em seguida, é desenvolvida
uma estratégia para tratar o contato lateral em poços com configuração
curvilínea. Depois disso, o problema de contorno livre é tratado mediante
uma estratégia que considera como a condição de borda evolui à medida que
a estrutura de perfuração avança. Isto é feito mediante uma formulação de
interação broca-rocha que deve considerar a dinâmica de corte. Para isso, uma
equação extra, de advecção, é resolvida junto com as equações de movimento
de Cosserat. Em seguida, alguns casos de aplicação são apresentados. Numa
primeira instancia, alguns elementos do problema são avaliados separadamente.
Seguidamente, eles são integrados e analisados de forma conjunta. Por exemplo,
primeiramente uma coluna de perfuração sem contato de fundo (off-bottom)
é simulada, ou seja, sem contato broca-rocha, para estudar o comportamento
e a implementação da estratégia para o contato lateral. Aqui também são
calibrados alguns dos parâmetros do modelo de atrito. Em seguida, a estratégia
para contabilizar o corte na rocha é implementada em um modelo 2-DOF de
baixa dimensão e em um semi-discreto onde a dinâmica de torção é modelada
como uma equação de onda. Os resultados mostram que o uso de abordagens
contínuas resulta mais apropriade que aquelas onde se utilizam modelos de
baixa dimensãom, particularmente quando são consideradas colunas longas,
e quando há interesse em analisar não apenas o comportamento da broca,
mas também o comportamento do sistema mecânico ao longo dos tubos de
perfuração. Isso é reforçado por outro exemplo onde a dinâmica de corte
é combinada com a formulação de Cosserat. Observações semelhantes do
ponto de vista qualitativo são encontradas. Resumindo os resultados obtidos,
as diferenças nas previsões dadas pelos modelos de baixa dimensão e o
de unidimensional de Cosserat justificam o desenvolvimento e aplicação da
abordagem com esta formulação em estruturas de perfuração. Finalmente, a
modo de introduzir outro aspecto importante em colunas de perfuração e que
pode ser uma linha de pesquisa para continuar o trabalho, a variabilidades
presente em elementos como rocha, inclui-se um caso de aplicação considerando
um poço horizontal e um campo estocástico de atrito. / [en] In this thesis, the theory of Cosserat rods is applied to the dynamics of
drill-strings. The main objective is to evaluate the behaviour of these strings
when they move within curved wells. To achieve this goal, a deterministic
structural model is constructed, where the drill-pipes and the bottom hole
assembly are taken as a Cosserat rod. Next, a strategy to deal with the
lateral contact in curved well configurations is developed. After that, the free
boundary problem is assessed: while drilling, the boundary changes due to
cutting, modifying the position of the soil and, consequently, changing the bit-rock interaction forces. For this reason, a bit-rock model that can account for
the cutting dynamics is adopted, in which an extra advection equation is solved
together with the equations of motion of the Cosserat rod. Next, application
cases are provided. First, some effects included in the model are tested in
isolation, such as the lateral friction, the lateral contact, and the cutting.
After that, they are all combined. In the first analysis, an off-bottom string is
simulated, i.e. without contact at the bit. This allows testing the formulation
associated with the lateral contact. Also, the calibration of the lateral friction
parameters is made. Following that, the strategy to account for the cutting
at the bit is implemented in a low-dimensional 2-DOF model, and in a semi-discrete model with a continuous wave equation for the torsional dynamics.
The results show that the use of continuous approaches is more appropriate
than low-dimensional models. Especially when long columns are considered,
and when there is interest in understanding not only the behaviour at the bit
but also along drill-pipes. This finding is reinforced by another application
where the cutting dynamics are combined with the Cosserat rod formulation.
Again, similar observations from a qualitative point of view are found. Overall,
the differences in the results between the lumped low-dimensional models and
the continuous Cosserat rod justify the development and application of the
Cosserat approach to drilling structures. Finally, an introductory stochastic
analysis concerning the variability of the rock is presented as an introduction
to a future line of research, where stochasticity is included. / [es] En esta tesis, la teoria de Cosserat para elementos unidimensionales es
revisitada y aplicada a la simulación de columnas de perforación. El objetivo
es estudiar el comportamiento de estas estructuras en pozos de geometría
curva. Para alcanzar este objetivo se construye un modelo determinístico.
En este modelo, los caños de perforación (drill-pipes) y el conjunto de fondo
(bottom hole assembly) son modelados como una estructura unidimensional de
Cosserat. Seguidamente, una estrategia para tratar con el contacto lateral en
pozos curvos es desarrollada. Luego, el problema de frontera libre es estudiado:
durante la perforación, la condición de borde cambia debido al cambio del perfil
altimétrico del terreno, alterando su posición y consecuentemente las fuerzas
asociadas a la interacción broca-roca. Por esta razón, se decide utilizar un
modelo de interacción broca-roca que tiene en cuenta la dinámica del corte.
En este abordaje una ecuación extra, la ecuación de advección, es resuelta en
forma acoplada con las ecuaciones del movimiento de la estructura de Cosserat.
Algunos ejemplos de aplicación son presentados. En una primera instancia,
algunos de los elementos del problema son estudiados en forma aislada. Luego
combinados en un modelo completo. Por ejemplo, el caso de una columna sin
contacto de fondo (off-bottom) es tratado para evaluar el comportamiento y la
implementación de la estrategia mencionada para detectar el contacto lateral.
Además, se efectúa la calibración de alguno de los parámetros relacionados
con la fricción lateral. Luego, la estrategia para considerar el corte en la punta
es implementada en un modelo de 2-DOF, y en otro semi-discreto donde se
considera un modelo de ecuación de onda para la dinámica torsional. Los
resultados muestran que el uso de formulaciones continuas es más apropiado
que aquellas formulaciones donde se utilizan modelos de dimensiones reducidas,
particularmente cuando se estudia columnas largas donde el interés se centra
en entender no solo el comportamiento de la broca sino también a lo largo de
la tubería. Este resultado es reforzado por otro caso de aplicación en donde
se combina la dinámica de corte con un modelo de Cosserat. Observaciones
similares son vistas en el comportamiento cualitativo de la solución. En
resumen, las diferencias observadas en los diferentes ejemplos de aplicación
entre los modelos de dimensiones reducidas y el modelo continuo de Cosserat
justifican el desarrollo y la aplicación de la teoría de Cosserat a estructuras de
perforación. Finalmente, dado que uno de los objetivos planteados también es
considerar la variabilidad en algunos elementos como ser las propiedades de la
roca, un caso de aplicación considerando un pozo horizontal es mostrado.
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